Manufacture of hacksaws or the like.



J. NEILL.

MANUFAGTURE 0F HACKSAWS OR THE LIKE.

APPLICATION HLED JUNE 23,1906.

907,167, y Patented Dec. 22,1908.

HWENTQIR) 1 WITMSSESH y d WM JAMllb' NEILL, 0F SHEFFlliLD, ENGLAND.

MANUFACTURE OF HACKSAWS OR THE LIKE.

Specification of Letters Patent.

Patented Dec. 22, 1908.

Application filed June 23, 1906. Serial No. 323,045.

To all whom it may concern:\

Be it known that I, JAMES NEILL, a subject of the King of Great Britain, residing at Shetlield, England, have invented certain new and uselul Improvements in the Manufacture of Haclisaws or the Like, of which the following is a specification.

rlhe object of the invention is to provide an improved and highly ellicient method oi manufacturing,r hack saws'and similar articles having anedge of great hardness and consequent durability, andV a back of such toughness as to compensate for the comparative brittleness of the edge, so as to prevent the frequent breakages which occur with saws the entire blade of which is of hard steel the product being of great uniformity and of accurately controllable structure, composition and properties.

A compound str-ip or ribbon is formed having high carbon steel at one edge and low carbon steel at the other edge, the two steels being integrally united to each other. The teeth of the saw are then formed on the high carbon edge, and the entire bar is subjected to any usual or suitable hardening process such, for example, as heating and quenching in oil. This hardening process is ell'ectivr-i only on high carbon steel. Consequently the edge ol the saw is given a temper ol great hardness, the degree being regulable by regulating the composition oll the corresponding edge of the strip, and by varying the conditions of the hardening,r operation.. At the saine time the low-carbon steel back ot' the saw is substantially unaltered l'rom its original tough nature. Ordinarily the strip will be quite thin, and the high carbon steel will extend throughout the thiclmess thereot'. Any desired ratio between the width ol' tough backing and the width ol' hard edge may be obtained by correspondingly proportioning the Widths of the low and high carbon steel respectively in the strip, such ratio being entirely independent ol' the bardening operation, and beinei therefore easily and accurately controllable.

The preferred method of making the strip is as follows: An ingot is cast ol' the two steels, one cast upon the other so that the;v are practiaclly integrally welded together to a billet of suitable size l'or rolling, andv the billet rolled to produce a strip or ribbon ol the thickness of the saw blade desired.

To roll a strip or ribbon o'l' the comparatively slight width ol" a hack saw` blade, calls for the making of an unusually small billet, and foralarge number ole rollinfroperations to reduce the width as Well as the thickness; and calls also for the triinniingot' two edges for each blade manutactmcd. ln order to reduce these items olI cxpcnsc. l preferably l'orrn the ingot with two strips ol` one sort of steel, one on each side o'll an intermediate strip of the other steel, ercntually producing a corresponding strip oll suitable width to produce two or more blades, and I then divide the composite strip along the center of the intermediate stecl. Such a strip olE multiple width requires only the trimming ol' the two outer edges plus a single longitudinal cut for each additional blade mamil'mturcd.

lre'l'erably the intermediate metal is the high-carbon steel, and the low-carbon steel is arranged at each side ol the intermediate strip, and I' preferably manufacture thc blades two at atiineiroin such a double bar by dividing it along the center olthe highcarbon steel.

Besides the advantage in. the lessened amount ol' manipulation and in thc l'ewer cuts to bc`1nade,lsuch a stripwitli vthe high carbon atthcccntcrhas distinct technical advantages. lt must be rcniclnlwrcd that the strip or ribbon is ol miti-cinc thinncss and "therefore very susccpt lble to ktho coolingr action ol thc atmosphcrein frolling. Ordinarily it 1s rolled lirst hot and Vhnally cold. li'

the high-carbon steel is at thc. outcr cdgjcs oll the strip instead olE at the center, it is crinliled as it comes out ol' the rolls, the tendency being particularly noticeable in excessively thin worli such as this; wht-reas when it is in the center, no suc-hcrinldinglv is observe( being: prevented apparently bythe fact that the high-carbon steel is hcld at cach edge by the sott carbon steel. Another decided advantage arisingr from the arranging o'l the highyarbon steel in the ccutcr, is its protection from becoming` burned or "tire-edged duringsr thc hot rollingr process. The edges ol such strips are always not iccably burned, so

and remain so throughout the subsmpicut t that by placingthestccl which is to'l'orm the operations. The ingot is then manipulated cdgrc oll thc tool ai thc center ol: the strip,

in the usual or any suitable way to reduce it better wearing` edge oll thc tool is insured 5 While the burning has no substantial disadlimited the bar of Fig. 3 split along the middle to make two bars; Fig. 6 shows one of the bars formed with teeth; Fig. 7 shows the same after the hardening operation; Fig. 8 illustrates another manner of carrying out the invention.

Referring tothe embodiment of the invention illustrated bythe accompanying drawings, an ingot A is cast ot' steel, preferably of high puritysuch as crucible steel, witlrubands B B of low-carbon steel or iron, and an intermediate band C of high carbon steel. The percentage ofcarbon is preferably so low as to take the parts B B out of the class which can be hardened by heating and quenching, although there may be sutticient carbon to permit of a slight hardening or even `a spring temper. The ingot is then reduced by the usual processes such as hammering or rolling, or both, to the compound strip D with the strips E and E of low-carbon steel extending along each edge of the intermediate strip F ot' high-carbon steel. The different steels are cast directly on each other in the formation ot' the ingot, so that during all the subsequent processes they remain practically integrallyunited to each other.

From the strip D two separate compound stri )s G G are obtained by dividing the strip D a ong the center ol' the intermediate strip F of high-carbon steel to 'form a high-carbon edge (ll H) upon each ot the strips G G respectively.

The strips G G are identical, and each serves to make one strip from which saw blades of any desired length are made.

Fig. 6 shows the h igh-carbon edge H formed with teeth J, the low-carbon back- E being unaltered.

The final step in the process consists in heating the toothed strip G and quenching it as explained, which operation results in a nished saw blade K (Fig. 7) having an edge L of eXtreme hardness, and a back M of ex.- treme toughness, the back M having suffered little or no change in its properties from those of the edge E ot the coin ound strip.

VThe width of the hart cned edge L and ot the tough back M. are accurately controllable by the proportioning of the quantities of! high-carbon and low-carbon steel tively in the ingot, and may be determined with great uniformity and accuracy. Liliewise the degree of hardness and toughness of the parts may be determined very accu-- rately and easily, and within a wide range,

respecl l i only by the capabilities of the niaterial, The treatment of the entire blade simphiies very much the operation of harden- .ing as compared with processes which attempt to treat the edge ot the blade and to l protect the back 'from treatment. The hardening process in the present case is determined as to its limits bythe nature of the material, and not by any special steps to be taken 'during the hardening. As long as the materials are laid ri ht in the beginning, a comparatively Simp e matter, the proper hardening by immersion calls for no special precautions whatever.

Making the strip of double width with one composition intermediate of two strips of the other, as shown in Fig. 3, eects a saving in the trimming or other cutting operations as previously explained, and placing the carbon strip F in the center, facilitates the rolling g operation and reduces the liability of burning the high-carbon steel; since this affects most the outside edges. f'The economy in cutting operations may be'y extended by making the stri even Wide enough for three or more saw bla es, alternating the strips ot the different Ametals so that each will'be successively an intermediate strip between two strips of the otherl kind. Fig. 8 shows such a method applied to the making of three strips from which theblades are made. The successive strips N N and N2 are formed from a multiple strip having one intermediate strip of high-carbon metal and one intermediate strip of low-carbon metal, as indicated by the shading.

By the use of this process a much higher carbonsteel may be provided for the edge of the saw than could safely be used where the steel is of the same carbon content throughout, and thus a saw ot greater durability and reliability may be obtained.

By extensive experiments I have found certain other and very unexpected advantages pcculiar to the use of this invention in in hack saws. It is quite possible for hack saw blades made according to this invention to be hardened in water and yet be perfectly tough, Whereas it is the absolutely universal custom to harden these very thin blades in oil, the reason being that it hard cast steel ing the process of tightening up in the hand trame would break while being stretched.

Though l have described with great particularity of detail certain specific embodiments of my invention, yet it is not to be un derstood therefrom that the invention is limitod to the specific embodiments disclosed.

Vario us modilications thereof maybe made from the invention.

TWhitt I claim is The method of manufacturing hack saws 5 and the like with a hard edge and e tougher beck, which consists in forming a compound strip or rihloon of high carbon steel at one edge and low carbon steel at the other, the two steels being integrally united, forming hy those skilled in the art, Without departure 10 teeth on the high carbon edge, and heating and quenching the entire strip, whereby the high carbon edge of the saw is hardened and the 10W carbon back is substantially unaltered in toughness.

In witness whereof, I have hereunto signed 1.5 my naine in the presence of two subscribing witnesses.

CHARLES M. PIERCE, DOMINGO A. USINA. 

